The Bush administration is proposing to spend billions of dollars rebuilding the country's nuclear weapons manufacturing industry, resuming the production of nuclear components and materials halted after the end of the Cold War.

Proposals in President Bush's 2004 budget would refurbish virtually every facet of the nuclear weapons complex, ranging from the nuclear test site in Nevada to the Savannah River plant in South Carolina.

There has been intense opposition in Washington to some aspects of President Bush's nuclear weapons policies. The Democrats have fought, for instance, a proposal to build a new generation of smaller warheads, which cleared a Senate committee last week. But there has been virtually no congressional dissent or debate over the president's proposed multibillion- dollar resuscitation of America's nuclear infrastructure.

The president's budget includes $320 million to build new plutonium cores -- known as "pits" -- for nuclear warheads, $40 million of which would be used to design a plant capable of producing 500 such pits a year.

An additional $135 million would go to restart production of tritium, which has not been produced by the government for more than a decade, and more funds would be spent in coming years.

The tritium, a gas that dramatically increases the force of thermonuclear explosions, will be produced at a commercial reactor in Watts Bar, Tenn. -- an unprecedented breaching of a long-standing policy that kept weapons work at military facilities.

While rebuilding plans were begun under President Bill Clinton, the current budget proposals advance the effort more broadly. Some arms experts say the proposals indicate the White House is planning on a far larger nuclear arsenal than that envisaged in the recently signed Moscow Treaty with Russia. The treaty, ratified by the Senate in March, mandates more than a 60 percent reduction in deployed warheads over the next decade.

"The clearest answer to what is happening comes from the fact that they want to build a pit production facility that can make 500 pits a year," said Robert Civiak, a scientist who formerly analyzed nuclear weapons spending at the Office of Management and Budget.

"Add to that the tritium production, and it's clear they want to support much more of a stockpile than what is in the Moscow Treaty. They're preparing the capacity to completely replace the existing stockpile in five to 10 years."

Further, according to Civiak, the fastest growing program in the budget of the National Nuclear Security Administration, which oversees the weapons complex, is the refurbishment of the rest of the industrial machinery of nuclear warhead production.

From 2001, when it was launched, through 2008, the rebuilding program is expected to cost nearly $2.5 billion, Civiak estimated in a recent analysis of the White House numbers.

RETURN OF NUCLEAR TESTING

The budget also includes $25 million to increase the readiness at the Nevada Test Site, so that a nuclear test could be arranged in as little as 18 months, down from the current limit of three years.

Nuclear testing has been banned since 1992, and the Bush administration has said it has no plans to resume underground blasts. But some arms experts and congressional Democrats charge that the proposed spending seems aimed at a resumption of testing.

"People don't realize that we're getting back into the nuclear bomb business in a big way, and it's a very expensive business," said Joseph Cirincione, director of the nonproliferation project at the Carnegie Endowment for International Peace.

Significant portions of the nuclear weapons infrastructure were shut down near the end of the Cold War, either because of severe environmental contamination, as at the Rocky Flats pit plant near Denver, or because of reduced needs, as the standoff with the former Soviet Union eased.

But upgrading the aging infrastructure is now regarded as a cornerstone of the Bush administration's more assertive defense strategy.

"That infrastructure is part of the nuclear deterrent," Linton Brooks, the administrator of the nuclear safety agency, said in an interview with The Chronicle.

Brooks added that the aim was to develop a more flexible U.S. nuclear complex that would not only maintain the existing stockpile of warheads "forever," but would also be able to respond to any new threats that might emerge.

"We can't predict the future," Brooks said. "We need to be able to respond to the unforeseen," by having the capability to produce new kinds of nuclear weapons quickly.

He strongly denied, however, that the aim was to maintain a nuclear stockpile larger than that permitted by the Moscow Treaty, a reduction from the 10,650 warheads now held by the military to somewhere between 2,200 and 1, 700 deployed in 2012. The facilities and components being developed would be used to maintain the effectiveness of the existing stockpile, Brooks insisted.

'STOCKPILE STEWARDSHIP'

Overall spending on nuclear weapons activities has doubled since its low point of $3 billion in 1995, to a proposed $6.4 billion in the next fiscal year, even though the stated mission, begun in the Clinton administration, is "stockpile stewardship" -- maintaining the weapons and certifying they will work as designed without testing.

"We already spend more today just to maintain the existing stockpile than we did on design and production during the Cold War," said Stephen Schwartz, publisher of the Bulletin of the Atomic Scientists. "That will only go higher if we restart things, as they are planning."

Some of the proposals may set dangerous precedents, say arms experts.

Kenneth Bergeron, a former nuclear scientist at the Sandia National Laboratory, warned in a recent book, "Tritium on Ice: The Dangerous New Alliance of Nuclear Weapons and Nuclear Power," that the decision to develop tritium at the Watts Bar reactor blurs the line between commercial and military reactors, something the United States has insisted other countries should not do.

He also disagrees with administration defenders who insist that new production of tritium is needed to maintain the existing arsenal. Bergeron said he believes enough of the material can be recycled from retired warheads for the military's purposes.

"The tritium developments are the first tangible action which show a commitment to expanding the arsenal," said Bergeron. "We're spending money, retraining workers. This is very real. It also represents an erosion of the restraints put in place at the end of the Cold War."

ORIGINS OF NEW DOCTRINE

The first signs of the administration's new nuclear policy came last January in its Nuclear Posture Review. The policy paper, produced by the Pentagon, said the United States should not just maintain the capability to launch large nuclear counterstrikes as a deterrent to nuclear powers, but should consider possibly striking pre-emptively at those countries developing nuclear, chemical or biological weapons.

The new doctrine has spurred a contentious debate in Congress, as has administration proposals to begin design work on a new generation of nuclear "bunker-busters" intended to destroy caches of prohibited weapons buried deep underground.

The president also has proposed repealing a decade-old law prohibiting the development of smaller, low-yield weapons. The law was intended to discourage other countries from developing what are regarded as more "usable" nuclear warheads.

Congressional committees are scheduled to continue debating the proposals next week.

The Senate Armed Services Committee on Thursday approved $15.5 million for research into the bunker-busters, officially called the Robust Nuclear Earth Penetrator. It set aside an additional $6 million for research into advanced nuclear concepts, and approved a repeal of the 10-year-old ban on the development of low-yield warheads. Democrats say there is little hope of halting the initiatives.

But there has been virtually no discussion of the far more costly proposals to rebuild the weapons production capability.

Rep. Ellen Tauscher, D-Walnut Creek, while expressing intense opposition to the administration's new nuclear posture, said she considered the rebuilding of the existing nuclear infrastructure prudent.

"We need to balance restraint with credibility," she said. "We have said, 'Let's not go out of the nuclear business.' We need to maintain our capability and not have cold production lines."

Still, the country retains an enormous stockpile of nuclear materials. The figures are now classified, but in 1999 the Energy Department said there were more than 12,000 plutonium pits in storage at the Pantex plant, near Amarillo, Texas, said Schwartz of the Bulletin of Atomic Scientists. In addition, there are nearly 200 tons of highly enriched uranium at the Oak Ridge Reservation in Tennessee.

The irony, say some analysts, is that for all the money to be spent on reviving the nuclear weapons complex, the prospect of the weapons actually being employed is slim.

"The reality is there aren't going to be many, if any, opportunities to use them," said Michael O'Hanlon, a military expert at the Brookings Institution who favors maintaining a powerful arsenal. "It's still a relatively unusable deterrent of last resort."

NUCLEAR WEAPONS ACROSS THE GLOBEThere are approximately 30,000 nuclear weapons in the world, more than 95 percent of them in the United States and Russia. Aside from the admitted nuclear powers, a number of countries are suspected by international arms monitors of having clandestine weapons or pursuing weapons programs. The Nuclear Non-Proliferation Treaty (NPT) went into effect in 1970. To date, 187 countries have ratified the NPT, which is monitored by the U.N. International Atomic Energy Agency (IAEA).

COUNTRIES WITH CONFIRMED NUCLEAR WEAPONSThe five major nuclear-armed states - the United States, Russia, China, France and Britain - are permanent members of the U.N. Security Council, and are bound under the NPT not to transfer nuclear weapons or to help nonnuclear states to obtain them. The other nuclear states, India and Pakistan, have not signed the NPT. United States: 10,500 nuclear warheads Russia: 20,000 warheads, half of which are deployed China: 400 warheads France: 450 warheads Britain: 185 warheads India: 65 warheads Pakistan: 30-50 warheads

COUNTRIES WITH UNCONFIRMED NUCLEAR WEAPONSIsrael: 100 (projected number) warheads; has not signed NPT. North Korea: 1-2 (projected number) warheads; announced its withdrawal from NPT in January.

COUNTRIES REPORTED TO BE PURSUING DEVELOPMENT OF NUCLEAR PROGRAMSAlgeria, Syria: Suspected intentions to produce nuclear weapons, but no nuclear weapons programs have been identified. Iran, Libya: Suspected of undertaking nuclear weapons programs since the early 1970s, but status of programs difficult to determine. Iraq: Nuclear weapons program started in the early 1970s, but was effectively halted in 1991 by Security Council-mandated inspections. After inspections ended in late 1998, it was suspected of resuming its quest for nuclear weapons, but U.S. troops have found no evidence to date in their post- war searches.

COUNTRIES THAT HAVE DISBANDED NUCLEAR WEAPONS PROGRAMSBelarus, Ukraine, Kazakhstan: Inherited nuclear weapons at the breakup of the Soviet Union, but returned the weapons to Russia and signed the Nuclear Non-Proliferation Treaty as a nonnuclear weapons state. Argentina: Admitted only that it conducted unsafeguarded uranium enrichment and reprocessing. Australia, Egypt: Ended their programs before they signed the NPT. Brazil, South Korea, Switzerland: Ended their programs before 1970. Romania: Former Warsaw Pact country once had a plutonium-separation program. South Africa: Abandoned its program before it signed the NPT in 1991, but maintains stockpiles of plutonium and highly enriched uranium under IAEA safeguards. Spain: May have had an unacknowledged nuclear weapons program under the previous military dictatorship. Sweden: Had a program that was essentially ended by the time it signed the NPT. Taiwan: Ended its program after 1970. Yugoslavia: The former communist government had a program that was ended after 1970.